The present invention relates to bulldozers or the like having transversely extending material moving blades, and more particularly, to an improved and simplified mechanism for angling, tilting, and pitching the material moving blade.
In non-angling types of known bulldozer blade arrangements, tilting of the blade has been accomplished conventionally by pivotally connecting the back of the blade to the forward end of the push arms of a C-shaped frame and providing extensible piston cylinders between the push arms and the top of the blade. Tilting of the blade in this known construction is accomplished by retracting the piston cylinder on one push arm and at the same time extending the piston cylinder on the other push arm.
In known angling types of bulldozer blades, the load handling blade is mounted on the earth moving equipment by means of a central swivel joint, one part of which is attached to the rear of the blade and the companion part is attached to the pusher frame of the earth moving equipment so as to permit pitch movement, pivotal side or angular movement, and edgewise tilting movement of the blade. Various problems occur in the design of such mechanism, particularly when in addition to the angling provision of the blade, tilting of the blade about a longitudinal axis is desired.
One type of prior art construction provides a pair of fluid cylinders attached to the rear of the blade at one end thereof and having their other end attached to the frame of the earth moving equipment, which, when selectively actuated, vary the angle of the blade by pivoting the blade around a vertical axis of the swivel joint relative to the longitudinal axis of the machine. Normally, to vary the vertical position of the blade edgewise for tilting, a separate fluid motor has been provided in addition to the fluid motors for angling of the blade.
With this prior arrangement, when the tilting motor is actuated to accomplish vertical tilt adjustment of the blade, the pair of angling motors are urged to move arcuately in opposite vertical directions. A problem with the prior art mounting arrangement is that the arrangement is subjected to excessive stresses, and the amount of tilt adjustment of the blade is restricted. It is wellknown that earth moving machines of this character are subject to considerable shock loads during operation and therefore must be of extremely rugged construction.
Another problem associated with these prior art blade control arrangements is that they have no tilt cylinder stroke available to tilt the blade when the blade is fully pitched forwardly or rearwardly. Thus, maximum tilt for the blade can only take place when the blade is in its mid-pitch position. In bulldozers, complete adjustability of the dozer blade renders the machine more versatile. Therefore, there has been a need for a simplified mechanical construction that permits complete adjustability of the blade.
A further problem with prior constructions occurs when an uneven load is applied to the blade during pitching or angling. If one side of the blade is under a load while the other side is not, the blade will follow the path of least resistance which may tilt the blade when pitching is desired. When the blade is set at a desired position such as for forming a ditch or leveling a road, the blade must be capable of maintaining the position selected.
These disadvantages of present bulldozer constructions have resulted in the adjustment and stabilizer construction for dozer blades of the present invention which effectively eliminates the above difficulties of the prior art.